At Mon, 2 Sep 2019 15:51:34 +0900, Michael Paquier <mich...@paquier.xyz> wrote in <20190902065134.ge1...@paquier.xyz> > On Mon, Sep 02, 2019 at 12:27:09AM +0000, Tsunakawa, Takayuki wrote: > > From: Tom Lane [mailto:t...@sss.pgh.pa.us] > >> After investigation, the mechanism that's causing that is that the > >> src/test/recovery/t/010_logical_decoding_timelines.pl test shuts > >> down its replica server with a mode-immediate stop, which causes > >> that postmaster to shut down all its children with SIGQUIT, and > >> in particular that signal propagates to a "cp" command that the > >> archiver process is executing. The "cp" is unsurprisingly running > >> with default SIGQUIT handling, which per the signal man page > >> includes dumping core. > > > > We've experienced this (core dump in the data directory by an > > archive command) years ago. Related to this, the example of using > > cp in the PostgreSQL manual is misleading, because cp doesn't > > reliably persist the WAL archive file. > > The previous talks about having pg_copy are still where they were a > couple of years ago as we did not agree on which semantics it should > have. If we could move forward with that and update the documentation > from its insanity that would be great and... The signal handling is > something else we could customize in a more favorable way with the > archiver. Anyway, switching from something else than SIGQUIT to stop > the archiver will not prevent any other tools from generating core > dumps with this other signal.
Since we are allowing OPs to use arbitrary command as archive_command, providing a replacement with non-standard signal handling for a specific command doesn't seem a general solution to me. Couldn't we have pg_system(a tentative name), which intercepts SIGQUIT then sends SIGINT to children? Might be need to resend SIGQUIT after some interval, though.. > > We enable the core dump in production to help the investigation just in > > case. > > So do I in some of the stuff I work on. > > > some_command also catches SIGQUIT just exit. It copies and syncs the file. > > > > I proposed something in this line as below, but I couldn't respond to > > Peter's review comments due to other tasks. Does anyone think it's worth > > resuming this? > > > > https://www.postgresql.org/message-id/7E37040CF3804EA5B018D7A022822984@maumau > > And I was looking for this thread a couple of lines ago :) > Thanks. # Is there any means to view the whole of a thread from archive? # I'm a kind of reluctant to wander among messages like a rat in # a maze:p regards. -- Kyotaro Horiguchi NTT Open Source Software Center
